const S0: [u8; 256] = [
    0x3e, 0x72, 0x5b, 0x47, 0xca, 0xe0, 0x00, 0x33, 0x04, 0xd1, 0x54, 0x98, 0x09, 0xb9, 0x6d, 0xcb,
    0x7b, 0x1b, 0xf9, 0x32, 0xaf, 0x9d, 0x6a, 0xa5, 0xb8, 0x2d, 0xfc, 0x1d, 0x08, 0x53, 0x03, 0x90,
    0x4d, 0x4e, 0x84, 0x99, 0xe4, 0xce, 0xd9, 0x91, 0xdd, 0xb6, 0x85, 0x48, 0x8b, 0x29, 0x6e, 0xac,
    0xcd, 0xc1, 0xf8, 0x1e, 0x73, 0x43, 0x69, 0xc6, 0xb5, 0xbd, 0xfd, 0x39, 0x63, 0x20, 0xd4, 0x38,
    0x76, 0x7d, 0xb2, 0xa7, 0xcf, 0xed, 0x57, 0xc5, 0xf3, 0x2c, 0xbb, 0x14, 0x21, 0x06, 0x55, 0x9b,
    0xe3, 0xef, 0x5e, 0x31, 0x4f, 0x7f, 0x5a, 0xa4, 0x0d, 0x82, 0x51, 0x49, 0x5f, 0xba, 0x58, 0x1c,
    0x4a, 0x16, 0xd5, 0x17, 0xa8, 0x92, 0x24, 0x1f, 0x8c, 0xff, 0xd8, 0xae, 0x2e, 0x01, 0xd3, 0xad,
    0x3b, 0x4b, 0xda, 0x46, 0xeb, 0xc9, 0xde, 0x9a, 0x8f, 0x87, 0xd7, 0x3a, 0x80, 0x6f, 0x2f, 0xc8,
    0xb1, 0xb4, 0x37, 0xf7, 0x0a, 0x22, 0x13, 0x28, 0x7c, 0xcc, 0x3c, 0x89, 0xc7, 0xc3, 0x96, 0x56,
    0x07, 0xbf, 0x7e, 0xf0, 0x0b, 0x2b, 0x97, 0x52, 0x35, 0x41, 0x79, 0x61, 0xa6, 0x4c, 0x10, 0xfe,
    0xbc, 0x26, 0x95, 0x88, 0x8a, 0xb0, 0xa3, 0xfb, 0xc0, 0x18, 0x94, 0xf2, 0xe1, 0xe5, 0xe9, 0x5d,
    0xd0, 0xdc, 0x11, 0x66, 0x64, 0x5c, 0xec, 0x59, 0x42, 0x75, 0x12, 0xf5, 0x74, 0x9c, 0xaa, 0x23,
    0x0e, 0x86, 0xab, 0xbe, 0x2a, 0x02, 0xe7, 0x67, 0xe6, 0x44, 0xa2, 0x6c, 0xc2, 0x93, 0x9f, 0xf1,
    0xf6, 0xfa, 0x36, 0xd2, 0x50, 0x68, 0x9e, 0x62, 0x71, 0x15, 0x3d, 0xd6, 0x40, 0xc4, 0xe2, 0x0f,
    0x8e, 0x83, 0x77, 0x6b, 0x25, 0x05, 0x3f, 0x0c, 0x30, 0xea, 0x70, 0xb7, 0xa1, 0xe8, 0xa9, 0x65,
    0x8d, 0x27, 0x1a, 0xdb, 0x81, 0xb3, 0xa0, 0xf4, 0x45, 0x7a, 0x19, 0xdf, 0xee, 0x78, 0x34, 0x60,
];

const S1: [u8; 256] = [
    0x55, 0xc2, 0x63, 0x71, 0x3b, 0xc8, 0x47, 0x86, 0x9f, 0x3c, 0xda, 0x5b, 0x29, 0xaa, 0xfd, 0x77,
    0x8c, 0xc5, 0x94, 0x0c, 0xa6, 0x1a, 0x13, 0x00, 0xe3, 0xa8, 0x16, 0x72, 0x40, 0xf9, 0xf8, 0x42,
    0x44, 0x26, 0x68, 0x96, 0x81, 0xd9, 0x45, 0x3e, 0x10, 0x76, 0xc6, 0xa7, 0x8b, 0x39, 0x43, 0xe1,
    0x3a, 0xb5, 0x56, 0x2a, 0xc0, 0x6d, 0xb3, 0x05, 0x22, 0x66, 0xbf, 0xdc, 0x0b, 0xfa, 0x62, 0x48,
    0xdd, 0x20, 0x11, 0x06, 0x36, 0xc9, 0xc1, 0xcf, 0xf6, 0x27, 0x52, 0xbb, 0x69, 0xf5, 0xd4, 0x87,
    0x7f, 0x84, 0x4c, 0xd2, 0x9c, 0x57, 0xa4, 0xbc, 0x4f, 0x9a, 0xdf, 0xfe, 0xd6, 0x8d, 0x7a, 0xeb,
    0x2b, 0x53, 0xd8, 0x5c, 0xa1, 0x14, 0x17, 0xfb, 0x23, 0xd5, 0x7d, 0x30, 0x67, 0x73, 0x08, 0x09,
    0xee, 0xb7, 0x70, 0x3f, 0x61, 0xb2, 0x19, 0x8e, 0x4e, 0xe5, 0x4b, 0x93, 0x8f, 0x5d, 0xdb, 0xa9,
    0xad, 0xf1, 0xae, 0x2e, 0xcb, 0x0d, 0xfc, 0xf4, 0x2d, 0x46, 0x6e, 0x1d, 0x97, 0xe8, 0xd1, 0xe9,
    0x4d, 0x37, 0xa5, 0x75, 0x5e, 0x83, 0x9e, 0xab, 0x82, 0x9d, 0xb9, 0x1c, 0xe0, 0xcd, 0x49, 0x89,
    0x01, 0xb6, 0xbd, 0x58, 0x24, 0xa2, 0x5f, 0x38, 0x78, 0x99, 0x15, 0x90, 0x50, 0xb8, 0x95, 0xe4,
    0xd0, 0x91, 0xc7, 0xce, 0xed, 0x0f, 0xb4, 0x6f, 0xa0, 0xcc, 0xf0, 0x02, 0x4a, 0x79, 0xc3, 0xde,
    0xa3, 0xef, 0xea, 0x51, 0xe6, 0x6b, 0x18, 0xec, 0x1b, 0x2c, 0x80, 0xf7, 0x74, 0xe7, 0xff, 0x21,
    0x5a, 0x6a, 0x54, 0x1e, 0x41, 0x31, 0x92, 0x35, 0xc4, 0x33, 0x07, 0x0a, 0xba, 0x7e, 0x0e, 0x34,
    0x88, 0xb1, 0x98, 0x7c, 0xf3, 0x3d, 0x60, 0x6c, 0x7b, 0xca, 0xd3, 0x1f, 0x32, 0x65, 0x04, 0x28,
    0x64, 0xbe, 0x85, 0x9b, 0x2f, 0x59, 0x8a, 0xd7, 0xb0, 0x25, 0xac, 0xaf, 0x12, 0x03, 0xe2, 0xf2,
];

const D: [u32; 16] = [
    0x44d7, 0x26bc, 0x626b, 0x135e, 0x5789, 0x35e2, 0x7135, 0x09af, 0x4d78, 0x2f13, 0x6bc4, 0x1af1,
    0x5e26, 0x3c4d, 0x789a, 0x47ac,
];

fn rol(x: u32, move_: i32) -> u32 {
    (x << move_) | (x >> (32 - move_))
}

fn l1(x: u32) -> u32 {
    x ^ rol(x, 2) ^ rol(x, 10) ^ rol(x, 18) ^ rol(x, 24)
}

fn l2(x: u32) -> u32 {
    x ^ rol(x, 8) ^ rol(x, 14) ^ rol(x, 22) ^ rol(x, 30)
}

fn s(a: u32) -> u32 {
    ((S0[(a >> 24) as usize] as u32) << 24)
        | ((S1[((a >> 16) & 0xff) as usize] as u32) << 16)
        | ((S0[((a >> 8) & 0xff) as usize] as u32) << 8)
        | (S1[(a & 0xff) as usize] as u32)
}

fn mod_add(a: u32, b: u32) -> u32 {
    let c = a as u64 + b as u64;
    ((c & 0x7fffffff) + (c >> 31)) as u32
}

fn mod_2exp_mul(x: u32, exp: usize) -> u32 {
    ((x << exp) | (x >> (31 - exp))) & 0x7fffffff
}

struct Cipher {
    lfsr: [u32; 16],
    x: [u32; 4],
    r1: u32,
    r2: u32,
    w: u32,
}

impl Cipher {
    fn new() -> Self {
        Self {
            lfsr: [0; 16],
            x: [0; 4],
            r1: 0,
            r2: 0,
            w: 0,
        }
    }

    fn lfsr_with_init_mode(&mut self, u: u32) {
        let mut v = mod_add(self.lfsr[0], mod_2exp_mul(self.lfsr[0], 8));
        v = mod_add(v, mod_2exp_mul(self.lfsr[4], 20));
        v = mod_add(v, mod_2exp_mul(self.lfsr[10], 21));
        v = mod_add(v, mod_2exp_mul(self.lfsr[13], 17));
        v = mod_add(v, mod_2exp_mul(self.lfsr[15], 15));
        v = mod_add(v, u);

        if v == 0 {
            v = 0x7fffffff;
        }

        self.lfsr.copy_within(1.., 0);
        self.lfsr[15] = v;
    }

    fn lfsr_with_work_mode(&mut self) {
        let mut v = mod_add(self.lfsr[0], mod_2exp_mul(self.lfsr[0], 8));
        v = mod_add(v, mod_2exp_mul(self.lfsr[4], 20));
        v = mod_add(v, mod_2exp_mul(self.lfsr[10], 21));
        v = mod_add(v, mod_2exp_mul(self.lfsr[13], 17));
        v = mod_add(v, mod_2exp_mul(self.lfsr[15], 15));

        if v == 0 {
            v = 0x7fffffff;
        }

        self.lfsr.copy_within(1.., 0);
        self.lfsr[15] = v;
    }

    fn bit_reconstruction(&mut self) {
        self.x[0] = ((self.lfsr[15] & 0x7FFF8000) << 1) | (self.lfsr[14] & 0xffff);
        self.x[1] = (self.lfsr[11] << 16) | (self.lfsr[9] >> 15);
        self.x[2] = (self.lfsr[7] << 16) | (self.lfsr[5] >> 15);
        self.x[3] = (self.lfsr[2] << 16) | (self.lfsr[0] >> 15);
    }

    fn f(&mut self) -> u32 {
        self.w = (self.x[0] ^ self.r1).wrapping_add(self.r2);
        let w1 = self.r1.wrapping_add(self.x[1]);
        let w2 = self.r2 ^ self.x[2];
        self.r1 = s(l1((w1 << 16) | (w2 >> 16)));
        self.r2 = s(l2((w2 << 16) | (w1 >> 16)));
        return self.w;
    }

    fn key_iv_insert(&mut self, k: &[u8; 16], iv: &[u8; 16]) {
        for i in 0..16 {
            // 8 + 15 + 8 = 31 bits
            self.lfsr[i] = (k[i] as u32) << 23 | D[i] << 8 | iv[i] as u32;
        }
    }

    fn init(&mut self, k: &[u8; 16], iv: &[u8; 16]) {
        self.key_iv_insert(k, iv);
        self.r1 = 0;
        self.r2 = 0;
        for _ in 0..32 {
            self.bit_reconstruction();
            self.f();
            self.lfsr_with_init_mode(self.w >> 1);
        }
    }

    fn keystream_generator(&mut self, keylen: usize) -> Vec<u32> {
        self.bit_reconstruction();
        self.f();
        self.lfsr_with_work_mode();

        let mut keystream = Vec::with_capacity(keylen);
        for _ in 0..keylen {
            self.bit_reconstruction();
            keystream.push(self.f() ^ self.x[3]);
            self.lfsr_with_work_mode();
        }
        keystream
    }

    fn encrypt(&mut self, input: &[u8]) -> Vec<u8> {
        let input = pkcs7_padding(input, 4);
        let keystream = self.keystream_generator(input.len() / 4);
        let mut result = Vec::new();
        for i in 0..input.len() {
            let z = keystream[i / 4];
            match i % 4 {
                0 => result.push(input[i] ^ (z >> 24) as u8),
                1 => result.push(input[i] ^ (z >> 16) as u8),
                2 => result.push(input[i] ^ (z >> 8) as u8),
                3 => result.push(input[i] ^ z as u8),
                _ => unreachable!(),
            }
        }
        result
    }
}

fn pkcs7_padding(input: &[u8], block_size: usize) -> Vec<u8> {
    let padding = block_size - input.len() % block_size;
    let mut result = Vec::from(input);
    for _ in 0..padding {
        result.push(padding as u8);
    }
    result
}

static BASE64_TABLE: &[u8; 64] =
    b"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

fn base64_encode(bytes: &[u8]) -> String {
    let mut result = String::new();
    for i in (0..bytes.len()).step_by(3) {
        let mut n = (bytes[i] as u32) << 16;
        if i + 1 < bytes.len() {
            n |= (bytes[i + 1] as u32) << 8;
        }
        if i + 2 < bytes.len() {
            n |= bytes[i + 2] as u32;
        }
        let n1 = (n >> 18) & 0x3f;
        let n2 = (n >> 12) & 0x3f;
        let n3: u32 = (n >> 6) & 0x3f;
        let n4 = n & 0x3f;
        result.push(BASE64_TABLE[n1 as usize].into());
        result.push(BASE64_TABLE[n2 as usize].into());
        result.push(if i + 1 < bytes.len() {
            BASE64_TABLE[n3 as usize].into()
        } else {
            '='
        });
        result.push(if i + 2 < bytes.len() {
            BASE64_TABLE[n4 as usize].into()
        } else {
            '='
        });
    }
    result
}

pub fn encryption(input: String) -> String {
    let key = [0u8; 16];
    let iv = [1u8; 16];
    let mut cipher = Cipher::new();
    cipher.init(&key, &iv);

    let result = cipher.encrypt(input.as_bytes());
    base64_encode(&result)
}
